add multiple items to cart at once

app/[locale]/product/[handle]/page.tsx

@@ -3,7 +3,7 @@ import { notFound } from 'next/navigation';
 import { Suspense } from 'react';
 
 import clsx from 'clsx';
-import { AddToCart } from 'components/cart/add-to-cart';
+import { AddManyToCart } from 'components/cart/add-many-to-cart';
 import { GridTileImage } from 'components/grid/tile';
 import Label from 'components/label';
 import { SupportedLocale } from 'components/layout/navbar/language-control';
@@ -135,7 +135,9 @@ export default async function ProductPage({
                 <div className="max-w-sm">
                   <VariantSelector options={product.options} variants={product.variants} />
 
-                  <AddToCart
+                  <AddManyToCart
+                    product={product}
+                    quantity={1}
                     variants={product.variants}
                     availableForSale={product.availableForSale}
                   />

components/cart/actions.ts

@@ -28,6 +28,37 @@ export const addItem = async (variantId: string | undefined): Promise<String | u
   }
 };
 
+export const addItems = async ({
+  variantId,
+  quantity = 1
+}: {
+  variantId: string | undefined;
+  quantity: number;
+}): Promise<String | undefined> => {
+  let cartId = cookies().get('cartId')?.value;
+  let cart;
+
+  if (cartId) {
+    cart = await getCart(cartId);
+  }
+
+  if (!cartId || !cart) {
+    cart = await createCart();
+    cartId = cart.id;
+    cookies().set('cartId', cartId);
+  }
+
+  if (!variantId) {
+    return 'Missing product variant ID';
+  }
+
+  try {
+    await addToCart(cartId, [{ merchandiseId: variantId, quantity }]);
+  } catch (e) {
+    return quantity === 1 ? 'Error adding item to cart' : 'Error adding items to cart';
+  }
+};
+
 export const removeItem = async (lineId: string): Promise<String | undefined> => {
   const cartId = cookies().get('cartId')?.value;
 

components/cart/add-many-to-cart.tsx

@@ -0,0 +1,117 @@
+'use client';
+
+import { ChevronDownIcon, ChevronUpIcon } from '@heroicons/react/24/outline';
+import clsx from 'clsx';
+import LoadingDots from 'components/loading-dots';
+import { Product, ProductVariant } from 'lib/shopify/types';
+import { useTranslations } from 'next-intl';
+import { useRouter, useSearchParams } from 'next/navigation';
+import { useState, useTransition } from 'react';
+import { addItems } from './actions';
+
+export function AddManyToCart({
+  product,
+  quantity = 1,
+  variants,
+  availableForSale
+}: {
+  product: Product;
+  quantity: number;
+  variants: ProductVariant[];
+  availableForSale: boolean;
+}) {
+  const router = useRouter();
+  const searchParams = useSearchParams();
+  const t = useTranslations('Index');
+
+  const [currentQuantity, setCurrentQuantity] = useState<number>(quantity);
+
+  const [isPending, startTransition] = useTransition();
+  const defaultVariantId = variants.length === 1 ? variants[0]?.id : undefined;
+  const variant = variants.find((variant: ProductVariant) =>
+    variant.selectedOptions.every(
+      (option) => option.value === searchParams.get(option.name.toLowerCase())
+    )
+  );
+  console.debug({ product, variant, currentQuantity });
+  const selectedVariantId = variant?.id || defaultVariantId;
+  const title = !availableForSale
+    ? t('cart.out-of-stock')
+    : !selectedVariantId
+    ? t('cart.options')
+    : undefined;
+
+  return (
+    <div className="flex flex-col space-y-2">
+      <div className="font-multilingual flex flex-row items-center space-x-2 border border-white/50">
+        <div className="px-3">{t('cart.quantity-label')}</div>
+        <input
+          value={currentQuantity}
+          onChange={(e) => setCurrentQuantity(Number(e.target.value))}
+          className={clsx(
+            'w-auto grow bg-transparent px-2 py-3 text-right text-white',
+            'outline-none focus:border-0 focus:outline-none focus:ring-0',
+            'focus-visible:ring-none focus-visible:border-none focus-visible:outline-none',
+            'focus-visible:ring-0 focus-visible:ring-offset-0',
+            'active:border-none active:outline-none active:ring-0'
+          )}
+        />
+        <div className="flex h-full flex-col space-y-px">
+          <button
+            onClick={() => setCurrentQuantity(currentQuantity ? currentQuantity + 1 : 1)}
+            className="grow px-2 py-0.5"
+          >
+            <span>
+              <ChevronUpIcon className="h-4 w-4" />
+            </span>
+          </button>
+          <button
+            onClick={() => setCurrentQuantity(currentQuantity > 0 ? currentQuantity - 1 : 0)}
+            className="grow px-2 py-0.5"
+          >
+            <span>
+              <ChevronDownIcon className="h-4 w-4" />
+            </span>
+          </button>
+        </div>
+      </div>
+      <button
+        aria-label="Add items to cart"
+        disabled={isPending || !availableForSale || !selectedVariantId}
+        title={title}
+        onClick={() => {
+          // Safeguard in case someone messes with `disabled` in devtools.
+          if (!availableForSale || !selectedVariantId) return;
+
+          startTransition(async () => {
+            const error = await addItems({
+              variantId: selectedVariantId,
+              quantity: currentQuantity
+            });
+
+            if (error) {
+              // Trigger the error boundary in the root error.js
+              throw new Error(error.toString());
+            }
+
+            router.refresh();
+          });
+        }}
+        className={clsx(
+          'relative flex w-full items-center justify-center bg-white p-4 font-serif text-xl tracking-wide text-black hover:opacity-90',
+          {
+            'cursor-not-allowed opacity-60 hover:opacity-60':
+              !availableForSale || !selectedVariantId,
+            'cursor-not-allowed': isPending
+          }
+        )}
+      >
+        {!isPending ? (
+          <span>{availableForSale ? t('cart.add') : t('cart.out-of-stock')}</span>
+        ) : (
+          <LoadingDots className="my-3 bg-black" />
+        )}
+      </button>
+    </div>
+  );
+}

messages/en.json

@@ -76,25 +76,27 @@
     "cart": {
       "add": "add to cart",
       "out-of-stock": "out of stock",
-      "title": "Shopping Bag",
+      "options": "please select options",
-      "subtitle": "Review your Order",
+      "quantity-label": "quantity",
-      "empty": "Your shopping bag is empty",
+      "title": "shopping bag",
-      "declinedCard": "We couldn't process the purchase. Please check your card information and try again.",
+      "subtitle": "review your order",
-      "thankYou": "Thank you for your order.",
+      "empty": "your shopping bag is empty",
-      "subtotal": "Subtotal",
+      "declinedCard": "we couldn't process the purchase. Please check your card information and try again.",
-      "taxes": "Taxes",
+      "thankYou": "thank you for your order.",
-      "taxCalculation": "Calculated at checkout",
+      "subtotal": "subtotal",
-      "shipping": "Shipping",
+      "taxes": "taxes",
-      "shippingCalculation": "Calculated at checkout",
+      "taxCalculation": "calculated at checkout",
-      "total": "Total",
+      "shipping": "shipping",
-      "proceed": "Proceed to Checkout",
+      "shippingCalculation": "calculated at checkout",
-      "continue": "Continue Shopping",
+      "total": "total",
-      "note": "Notes",
+      "proceed": "proceed to Checkout",
-      "notePlaceholder": "Enter any notes you would like to include with your order",
+      "continue": "continue Shopping",
-      "addNote": "Add a note to your order",
+      "note": "notes",
-      "editNote": "Edit note",
+      "notePlaceholder": "enter any notes you would like to include with your order",
-      "hideNote": "Hide",
+      "addNote": "add a note to your order",
-      "saving": "Saving...",
+      "editNote": "edit note",
+      "hideNote": "hide",
+      "saving": "saving...",
       "addFeaturedProduct": "+ add"
     },
     "age-gate": {

messages/ja.json

@@ -76,6 +76,8 @@
     "cart": {
       "add": "カートに入れる",
       "out-of-stock": "品切れ中",
+      "options": "オプション",
+      "quantity-label": "購入数",
       "title": "ショッピングカード",
       "subtitle": "ご注文内容の確認",
       "empty": "買い物袋が空っぽ",